---
title: "Keyboard"
id: 57285
type: "computer_media"
slug: "keyboard"
url: "http://localhost/computer_media/keyboard/"
markdown_url: "http://localhost/computer_media/keyboard.md"
published_at: "2024-10-04T08:06:01+00:00"
modified_at: "2026-03-30T21:18:38+00:00"
author: "David Anderson"
featured_image:
  url: "http://localhost/wp-content/uploads/2024/10/173_Kbd.png"
excerpt: "A ten-round typing reaction game flashes a random character on screen and waits for you to hit the matching key — how fast can you respond?"
category:
  - name: "Archived Media"
    slug: "archived-media"
    taxonomy: "category"
    url: "http://localhost/category/archived-media/"
post_tag:
  - name: "Downloadable"
    slug: "downloadable"
    taxonomy: "post_tag"
    url: "http://localhost/tag/downloadable/"
  - name: "TS 1000"
    slug: "ts1000"
    taxonomy: "post_tag"
    url: "http://localhost/tag/ts1000/"
model:
  - name: "Timex/Sinclair 1000"
    slug: "ts-1000"
    taxonomy: "model"
    url: "http://localhost/model/ts-1000/"
genre:
  - name: "Tutorial"
    slug: "tutorial"
    taxonomy: "genre"
    url: "http://localhost/type/tutorial/"
media_contents:
  - id: 56734
    title: "Timex Sinclair Public Domain Library Tape 1003"
    type: "computer_media"
    url: "http://localhost/computer_media/timex-sinclair-public-domain-library-tape-1003/"
media_type: "Program"
mediadate: "198x"
images:
  - url: "http://localhost/wp-content/uploads/2024/10/173_Kbd.png"
media_type_tags: "Tutorial"
---

This program is a simple keyboard reaction trainer that challenges the player to identify and type a randomly displayed character within a short time window. On each of ten rounds, a random character from CHR$(28) to CHR$(62) is shown briefly, then cleared, and INKEY$ is used to capture the player’s single-keystroke response. A short busy-wait loop at lines 80–90 provides a fixed display window before reading input. Correct responses increment a score counter via a GOSUB subroutine, and the final score is printed after all ten rounds.

***

## Program Analysis

### Program Structure

The program is organised into three logical sections:

1. **Initialisation (lines 1–10):** Clear screen and set score `N` to zero.
2. **Main game loop (lines 20–130):** Ten iterations, each showing a random character, pausing, reading a keypress, and checking for a match.
3. **End-of-game (lines 140–170):** Display final score, wait for ENTER via `INPUT I$`, then restart with `RUN`.

A short subroutine at lines 200–240 handles a correct answer: it increments the score, briefly prints “YES”, waits, and returns.

### Timing Mechanism

Two busy-wait loops are used for timing. The first (lines 30–40) introduces a random delay before displaying the target character, with `B` iterating from 0 to `RND*100+50`, giving a range of roughly 50–150 iterations. The second (lines 80–90) provides a fixed 30-iteration window during which the character remains visible before `INKEY$` is read at line 100. These loops are simple `FOR/NEXT` busy-waits with no body, a common idiom on this platform where a hardware timer or interrupt-driven delay is unavailable in BASIC.

### Character Generation

The target character is generated at line 50 as `CHR$(28+35*RND)`. Since `RND` returns a value in [0,1), this yields character codes in the range 28–62 inclusive. This range includes several non-printable or control characters at the low end (codes 28–31) as well as printable ASCII characters from space (32) through `>` (62). This means some rounds may display invisible or oddly-behaving characters, which is a subtle bug — the intent was likely to restrict to visible printable characters.

### Input Handling

`INKEY$` at line 100 reads a single keystroke without waiting. If no key is pressed at the moment of execution, `C$` remains `""` (set at line 70) and the comparison at line 110 simply fails. There is no second chance within a round; the player has only the instant the INKEY$ statement executes to have the correct key held down.

### Key BASIC Idioms

- `FOR B=0 TO RND*100+50: NEXT B` — random-length busy-wait loop.
- `LET C$="": ... LET C$=INKEY$` — pre-clear before reading so a missed keypress leaves an empty string.
- `INPUT I$` as a “press ENTER to continue” gate before `RUN`.
- `RUN` at line 170 to restart the entire program, resetting all variables.

### Score Tracking

The score variable `N` is incremented only inside the subroutine at line 200, called exclusively when the typed character exactly matches the displayed one (line 110). Because `RUN` at line 170 re-executes from line 1, `N` is correctly reset to 0 at line 10 at the start of each new game.

### Bugs and Anomalies

| Line | Issue | Effect |
| --- | --- | --- |
| 50 | `CHR$(28+35*RND)` can produce character codes 28–31 | Control characters may be displayed, making the round unwinnable or visually confusing |
| 80–90 | Fixed 30-iteration busy-wait before INKEY$ | Display window is extremely short; most keypresses will be missed |
| 100 | Single `INKEY$` sample with no loop | Player must hold key at exactly that moment; no polling window |

## Source Code

```
   1 REM "KEYBOARD"
   5 CLS 
  10 LET N=0
  20 FOR M=1 TO 10
  30 FOR B=0 TO RND*100+50
  40 NEXT B
  50 LET B$=CHR$ (28+35*RND)
  60 PRINT B$
  70 LET C$=""
  80 FOR B=0 TO 30
  90 NEXT B
 100 LET C$=INKEY$
 110 IF C$=B$ THEN GOSUB 200
 120 CLS 
 130 NEXT M
 140 PRINT "SCORE= ";N
 150 PRINT ,,,,"PRESS N/L"
 160 INPUT I$
 170 RUN 
 200 LET N=N+1
 210 PRINT "YES"
 220 FOR B=0 TO 20
 230 NEXT B
 240 RETURN 
 250 SAVE "1017%3"
 260 LIST
```